The judge approved the stay and now all of the authorities involved in Couch's detention will have to explain how the actions they took were consistent with the law.

It is a process that could take up to two months, the lawyer believes. But what are the chances of winning the case?

"At this point, I honestly would not venture to give out odds on this," he says.

"I find it in poor taste. I think we need to get the response back from the authorities. Once I know what their position is, I can tell you if they are right or wrong."

First of all, he has to talk to his client. On Tuesday, Mr Benitez will meet with Ethan Couch and explain what the implications are and ask whether he is willing to spend several months in Mexico to fight his corner.

Image copyrightAPImage caption
Couch is being held at the Agujas immigration detention centre in Mexico City

One thing though the lawyer is sure about - arguing against deportation will not work.

"The Mexican constitution provides for an executive order from the president where he can take any foreigner out without cause," he says.

"If the president deems it necessary to kick a foreigner out of Mexico, he can do it on his authority, no trial, no judge, nothing."

Mexico and the US have had an extradition treaty since 1978 but Benitez says he knows why it has not been used in this case.

"It would be a tough sell for the US to tell Mexico, you know what, this man was tried as a juvenile, pled guilty, was handed down his sentence and now 5 years later we don't think the sentence is fair and we want to retry him as an adult," he says.

"Mexico is never going to go along with that."

Deportation or extradition

"They said this guy didn't stamp his passport on the point of entry so we are going to kick him out," he says.

"In a sense, what is happening is that they are using deportation in lieu of extradition. I'll bet you a million dollars that 99.9% of the tourists in Puerto Vallarta as we speak did not stamp their passport - are you going to deport all of them too?"

And that, he expects, will be the basis of any argument to help Ethan Couch.

Image copyrightPolice handoutImage caption
Wanted posters were issued for Ethan Couch in the US

"We need to raise a new argument, an innovative argument to say deportation is not really deportation in this case - there's an extradition disguised as a deportation here.

"He's not being expelled because he didn't stamp his passport. He's being expelled because the Americans are waiting for him to subject him to a criminal trial."

For those who question how Mr Benitez can sleep at night, he reassures them.

"I sleep like a baby," he says. "You can't appease everybody so I am going to appease myself and I am going to do what I think is right.

"I have more experience than most people in dealing with what's right and wrong so I am going to let my own moral compass be the guide."